U.S. patent application number 13/541091 was filed with the patent office on 2012-10-25 for generation interpolation frames.
This patent application is currently assigned to PANASONIC CORPORATION. Invention is credited to Yukinaga SEKI, Hidetoshi Takeda.
Application Number | 20120268561 13/541091 |
Document ID | / |
Family ID | 46757432 |
Filed Date | 2012-10-25 |
United States Patent
Application |
20120268561 |
Kind Code |
A1 |
SEKI; Yukinaga ; et
al. |
October 25, 2012 |
GENERATION INTERPOLATION FRAMES
Abstract
The instant application describes a stereoscopic video
processing system that includes a vector detector configured to
detect a motion vector associated with frames of an input video
signal; an output image generator configured to generate an output
video signal by generating interpolation frames, and arranging the
frames of the input video signal and the interpolation frames along
a time axis; an output controller configured to control
interpolation phases associated with the interpolation frames; and
a feature amount calculator configured to calculate a feature
amount in image regions of the frames of the input video signal
used for generating the interpolation frames. The output image
generator is configured to generate the interpolation frames by
generating an interpolation image in an image region having the
feature amount larger than a threshold and by using the input video
signals without change in other image regions.
Inventors: |
SEKI; Yukinaga; (Kyoto,
JP) ; Takeda; Hidetoshi; (Osaka, JP) |
Assignee: |
PANASONIC CORPORATION
Osaka
JP
|
Family ID: |
46757432 |
Appl. No.: |
13/541091 |
Filed: |
July 3, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2011/004933 |
Sep 2, 2011 |
|
|
|
13541091 |
|
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Current U.S.
Class: |
348/43 ;
348/E13.064 |
Current CPC
Class: |
H04N 5/144 20130101;
H04N 13/128 20180501; G06T 3/4007 20130101; H04N 13/111
20180501 |
Class at
Publication: |
348/43 ;
348/E13.064 |
International
Class: |
H04N 13/00 20060101
H04N013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 3, 2011 |
JP |
2011-046688 |
Claims
1. A stereoscopic video processing system comprising: a vector
detector configured to detect a motion vector associated with
frames of an input video signal; an output image generator
configured to generate an output video signal by generating
interpolation frames based on the frames of the input video signal
and the motion vector, and arranging the frames of the input video
signal and the interpolation frames along a time axis; an output
controller configured to control interpolation phases associated
with the interpolation frames; and a feature amount calculator
configured to calculate a feature amount in image regions of the
frames of the input video signal used for generating the
interpolation frames, wherein the output image generator is
configured to generate the interpolation frames by generating an
interpolation image in an image region having the feature amount
larger than a threshold and by using the input video signals
without change in other image regions.
2. The stereoscopic video processing system of claim 1, wherein the
feature amount is a parameter representing a high-frequency
component contained in the image region.
3. The stereoscopic video processing system of claim 1, wherein the
feature amount is a parameter representing contrast in the image
region.
4. The stereoscopic video processing system of claim 1, wherein:
the stereoscopic video processing system includes a right frame
frequency converter for processing a right input video signal and a
left frame frequency converter for processing a left input video
signal, the right frequency converter includes the vector detector,
the output image generator, the feature amount calculator, and the
output controller, and the left frequency converter includes the
vector detector, the output image generator, the feature amount
calculator, and the output controller.
5. The stereoscopic video processing system of claim 2, wherein the
stereoscopic video processing system includes a right frame
frequency converter for processing a right input video signal and a
left frame frequency converter for processing a left input video
signal, the right frequency converter includes the vector detector,
the output image generator, the feature amount calculator, and the
output controller, and the left frequency converter includes the
vector detector, the output image generator, the feature amount
calculator, and the output controller.
6. The stereoscopic video processing system of claim 3, wherein the
stereoscopic video processing system includes a right frame
frequency converter for processing a right input video signal and a
left frame frequency converter for processing a left input video
signal, the right frequency converter includes the vector detector,
the output image generator, the feature amount calculator, and the
output controller, and the left frequency converter includes the
vector detector, the output image generator, the feature amount
calculator, and the output controller.
7. The stereoscopic video processing system of claim 1, wherein the
stereoscopic video processing system time-shares a single frame
frequency converter including the vector detector, the output image
generator, the feature amount calculator, and the output
controller.
8. The stereoscopic video processing system of claim 2, wherein the
stereoscopic video processing system time-shares a single frame
frequency converter including the vector detector, the output image
generator, the feature amount calculator, and the output
controller.
9. The stereoscopic video processing system of claim 3, wherein the
stereoscopic video processing system time-shares a single frame
frequency converter including the vector detector, the output image
generator, the feature amount calculator, and the output
controller.
10. A stereoscopic video display system comprising: an input image
selector configured to receive a stereoscopic video signal, and
output a right input video signal and a left input video signal,
each having a first frame frequency; the stereoscopic video
processing system of claim 1 processing the right and left input
video signals; and a display configured to perform frame sequential
display of a right output video signal and a left output video
signal, each having a second frame frequency, output from the
stereoscopic video processing system of claim 1.
11. A stereoscopic video processing method comprising steps of:
detecting a motion vector associated with frames of an input video
signal; generating interpolation frames based on the frames of the
input video signal and the motion vector; generating an output
video signal by arranging the frames of the input video signal and
the interpolation frames along a time axis; and calculating a
feature amount in image regions of the frames of the input video
signal used for generating the interpolation frames, wherein
generating the interpolation frames includes generating an
interpolation image in an image region having the feature amount
larger than a threshold and using the input video signal without
change in the other image region.
12. The method of claim 11, wherein the feature amount is a
parameter representing a high-frequency component contained in the
image region.
13. The method of claim 11, wherein the feature amount is a
parameter representing contrast in the image region.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation of PCT International Application
PCT/JP2011/004933 filed on Sep. 2, 2011, which claims priority to
Japanese Patent Application No. 2011-046688 filed on Mar. 3, 2011.
The disclosures of these applications including the specifications,
the drawings, and the claims are hereby incorporated by reference
in their entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to a stereoscopic video
processing system configured to detect motion vectors between right
and left image frames of stereoscopic video signals and generate
interpolation frames using the detected motion vectors, and more
particularly to a stereoscopic video processing system configured
to convert three-dimensional movies filmed at a frame frequency of
24 Hz to stereoscopic video images of 60 Hz and perform frame
sequential display at 120 Hz.
BACKGROUND
[0003] In recent years, 3D movies of a binocular disparity type
have been rapidly spread, which provide right and left eyes of
viewers with different images so that the viewers recognize the
three-dimensional effect. Showing 3D movies at theaters and
watching 3D movies at home with 3D enabled devices are becoming
common.
[0004] The 3D enabled devices for watching 3D movies at home
usually employ liquid crystal shutter glasses. With the liquid
crystal shutter glasses, right and left images are alternately
displayed on a display (i.e., frame sequential display). A viewer
wears the liquid crystal shutter glasses, which shut images coming
into the right or left eye in synchronization with the display of
an image. This allows the viewer to recognize the right image with
the right eye, and the left image with the left eye. As a result,
the viewer perceives the three-dimensional effect created by the
binocular disparity between the right and left images.
[0005] In general, while movies are filmed at a frame frequency of
24 Hz, they are displayed at a frame frequency of 60 Hz under the
NTSC system on home television sets. When a two-dimensional video
image of 24 Hz is converted to a video image of 60 Hz, frame
frequency conversion (i.e., telecine conversion) by 3:2 pull-down
may be performed. In the 3:2 pull-down, a single frame of 24 Hz may
be alternately displayed as three frames and two frames of 60
Hz.
[0006] FIG. 7 illustrates an example where a ball crossing a screen
is filmed at 24 Hz and displayed at 60 Hz after performing 3:2
pull-down. As shown, in 3:2 pull-down, the first frame of 24 Hz is
displayed as three frames, the second frame of 24 Hz is displayed
as two frames, and the third frame of 24 Hz is displayed as three
frames. When a human views something moving uniformly like in this
example, it is known that the line of sight moves so as to follow
the motion.
[0007] FIG. 8 illustrates the relationship between time and the
display position of the ball shown in FIG. 7. As shown in FIG. 8,
the line of sight follows the displayed ball and moves along the
track of the line of sight indicated by the arrow. In the graph,
while the position of the ball coincides with the track of the line
of sight on frames 2 and 7, the position of the ball does not
coincide with the track of the line of sight on the other frames.
For example, the ball appears behind the track of the line of sight
on frames 1, 4, and 6, and appears in front of the track of line of
sight on frames 3, 5, and 8. As such, the uniformly moving ball
seems to blur back and forth. This state is called a film judder,
which can largely influence the image quality in a stereoscopic
video image. An example will be described where the right and left
images of the scene of FIG. 7 are filmed in 3D at 24 Hz.
[0008] FIG. 9 illustrates the relationship between time and the
display position of the ball where a stereoscopic video image of 24
Hz is converted to right and left video images of 60 Hz by 3:2
pull-down and displayed by frame sequential display at 120 Hz.
[0009] FIG. 10 illustrates deviation of the display position of the
ball from the centers of the lines of sight from the right and left
eyes and the binocular disparity caused by the deviation. As shown,
when a stereoscopic video image of 24 Hz is converted to a
stereoscopic video image of 60 Hz by 3:2 pull-down and displayed by
frame sequential display at 120 Hz, the degree of the binocular
disparity of an output image non-uniformly fluctuates in a range
between N-2/5 V and N+3/5 V, where a degree of the binocular
disparity between the right and left images of an input image is N,
and the movement amount of the input image between frames is V.
[0010] With respect to a stereoscopic video image of the binocular
disparity type, a viewer recognizes the three-dimensional effect
based on the degree of the binocular disparity. If the degree of
the binocular disparity non-uniformly fluctuates between the frames
due to film judder as shown in FIG. 10, the viewer cannot precisely
recognize the three-dimensional effect. In addition, the viewer is
forced to three-dimensionally see a hard-to-see image, which could
cause eyestrain.
[0011] Accordingly, there is a need for a stereoscopic video
processing system, which can reduce such deterioration in the image
quality caused by 3:2 pull-down.
SUMMARY
[0012] In one general aspect, the instant application describes a
stereoscopic video processing system that includes a vector
detector configured to detect a motion vector associated with
frames of an input video signal; an output image generator
configured to generate an output video signal by generating
interpolation frames based on the frames of the input video signal
and the motion vector, and arranging the frames of the input video
signal and the interpolation frames along a time axis; an output
controller configured to control interpolation phases associated
with the interpolation frames; and a feature amount calculator
configured to calculate a feature amount in image regions of the
frames of the input video signal used for generating the
interpolation frames. The output image generator is configured to
generate the interpolation frames by generating an interpolation
image in an image region having the feature amount larger than a
threshold and by using the input video signals without change in
other image regions.
[0013] The above general aspect includes one or more of the
following features. The feature amount may be a parameter
representing a high-frequency component contained in the image
region. The feature amount may be a parameter representing contrast
in the image region. The stereoscopic video processing system may
include a right frame frequency converter for processing a right
input video signal and a left frame frequency converter for
processing a left input video signal. The right frequency converter
may include the vector detector, the output image generator, the
feature amount calculator, and the output controller. The left
frequency converter may include the vector detector, the output
image generator, the feature amount calculator, and the output
controller.
[0014] The stereoscopic video processing system may time-share a
single frame frequency converter including the vector detector, the
output image generator, the feature amount calculator, and the
output controller.
[0015] In another general aspect, the instant application describes
a stereoscopic video display system that includes an input image
selector configured to receive a stereoscopic video signal, and
output a right input video signal and a left input video signal,
each having a first frame frequency; the stereoscopic video
processing system processing the right and left input video
signals; and a display configured to perform frame sequential
display of a right output video signal and a left output video
signal, each having a second frame frequency, output from the
stereoscopic video processing system.
[0016] In another general aspect, the instant application describes
a stereoscopic video processing method that includes steps of:
detecting a motion vector associated with frames of an input video
signal; generating interpolation frames based on the frames of the
input video signal and the motion vector; generating an output
video signal by arranging the frames of the input video signal and
the interpolation frames along a time axis; and calculating a
feature amount in image regions of the frames of the input video
signal used for generating the interpolation frames. Generating the
interpolation frames includes generating an interpolation image in
an image region having the feature amount larger than a threshold
and using the input video signal without change in the other image
region.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The figures depict one or more implementations in accord
with the present teachings, by way of example only, not by way of
limitations. In the figures, like reference numerals refer to the
same or similar elements.
[0018] FIG. 1 illustrates an exemplary stereoscopic video display
system of the instant application;
[0019] FIG. 2 illustrates an exemplary motion vector detected
between two frames of the input signal;
[0020] FIG. 3 illustrates an exemplary timing relationship between
an input video signal, a previous frame video signal, a detected
motion vector, a motion vector for interpolation, a previous and
next frame video signal, and a interpolation phases;
[0021] FIG. 4 illustrates an exemplary interpolation frame;
[0022] FIG. 5 illustrates the appearance of a stereoscopic video
image created by a film dejudder of the stereoscopic video display
system shown in FIG. 1;
[0023] FIG. 6 illustrates the degree of binocular disparity of a
stereoscopic video image created by a film dejudder of the
stereoscopic video display system shown in FIG. 1;
[0024] FIG. 7 illustrates an example where a ball crossing a screen
is filmed at 24 Hz and displayed at 60 Hz after performing 3:2
pull-down;
[0025] FIG. 8 illustrates the relationship between time and the
display position of the ball shown in FIG. 7;
[0026] FIG. 9 illustrates an appearance of a stereoscopic video
image created by 3:2 pull-down;
[0027] FIG. 10 illustrates the degree of binocular disparity of a
stereoscopic video image created by 3:2 pull-down; and
[0028] FIG. 11 illustrates the relationship between the time and
the display position of the ball where the scene of FIG. 7 is
subject to a film dejudder.
DETAILED DESCRIPTION
[0029] In the following detailed description, numerous specific
details are set forth by way of examples in order to provide a
thorough understanding of the relevant teachings. However, it
should be apparent to those skilled in the art that the present
teachings may be practiced without exemplary details. In other
instances, well known methods, procedures, components, and
circuitry have been described at a relatively high-level, without
detail, in order to avoid unnecessarily obscuring aspects of the
present concepts.
[0030] In exchange for the present disclosure herein, the
Applicants desire all patent rights described in the claims.
Therefore, the patent rights are not intended to be limited or
restricted by the following detailed description and accompanying
figures.
[0031] The instant application describes a stereoscopic video
processing system configured to perform frame frequency conversion
suitable for stereoscopic video images. In the stereoscopic video
processing system of the instant application, when a stereoscopic
video image of 24 Hz is converted to a stereoscopic video image of
60 Hz, interpolation frames are generated using a motion vector
detected on part of frames, which largely influence the binocular
disparity between the right and left images.
[0032] Usually, the motion vectors are detected from a
two-dimensional video image of 24 Hz, and interpolation frames
synchronizing with the display timing of an image of 60 Hz are
generated using the motion vectors and displayed, thereby enabling
display of smooth motion without unnaturalness. See, e.g., Japanese
Patent Publication Number H09-172618. Such frame frequency
conversion is called film dejudder.
[0033] FIG. 11 illustrates the relationship between the time and
the display position of the ball where the scene of FIG. 7 is
subject to a film dejudder. The film dejudder generates and
displays interpolation frames having phases shifted from the
original frames 3 and 4 of 24 Hz by +0.4 and +0.8 frames,
respectively. The film dejudder also generates and displays
interpolation frames having phases shifted from the original frames
5 and 6 of 24 Hz by +0.2 and +0.6 frames, respectively. With
respect to the frames 2 and 7, the original frames of 24 Hz are
displayed without change. As a result, the display position of the
moving ball coincides with the track of the line of sight, and
smooth motion free from film judder can be provided. In addition,
in the case of a stereoscopic video image, the film dejudder
generates an interpolation frame which allows a moving object to
coincide with the track of the line of sight. This stabilizes the
degree of the binocular disparity, and as a result, the viewer more
easily obtains the three-dimensional effect.
[0034] Since a motion vector used in frame frequency conversion is
detected by comparing continuous frames, the movement of an object
may be accurately detected. However, movement such as rotation and
scaling may not be accurately detected. In addition, a correct
motion vector may not be detected in a region included in only one
of the continuous frames such as a region hidden in the background
of the moving object, the region appearing from the background, and
deformation of the object. Moreover, a motion vector is usually
detected by searching a predetermined range from the block to be
detected. When motion out of the search range occurs, a correct
motion vector may not be detected.
[0035] When a correct motion vector is not detected, it is known
that noise called a halo occurs around the moving object on an
interpolation frame and in a video image formed of continuous
interpolation frames. Halos are caused by incorrect interpolation
frames, and thus frequently occur where the ratio of interpolation
frames to displayed frames is high or where interpolation frames
are displayed for a long time. When a stereoscopic video image of
24 Hz is converted to a stereoscopic video image of 60 Hz and
displayed, an interpolation error could hinder establishment of
correspondence between the right and left images and the viewer may
not three-dimensionally see the image or may suffer eyestrain.
[0036] The stereoscopic video processing system is configured to
reduce or eliminate interpolation errors to allow the view to more
easily experience three-dimensional image or less eyestrain. To
this end, in the stereoscopic video processing system of the
instant application, when a stereoscopic video image of 24 Hz is
converted to a stereoscopic video image of 60 Hz, interpolation
frames are generated using a motion vector detected on part of
frames, which largely influence the binocular disparity between the
right and left images.
[0037] FIG. 1 illustrates an exemplary stereoscopic video display
system 100 of the instant application. The stereoscopic video
display system 100 includes an input image selector 1, a
stereoscopic video processing system 2, and a display 3. The
stereoscopic video processing system 2 includes right and left
frame frequency converters 20, each of which includes a video
memory 202, a vector detector 203, an output controller 204, a
vector memory 205, an output image generator 206, and a feature
amount calculator 207.
[0038] The input image selector 1 divides an input stereoscopic
video signal 101 into right and left input video signals 102 and
outputs the signals 102 to the stereoscopic video processing system
2. The stereoscopic video signal 101 alternately includes right and
left images of a frame frequency of 60 Hz. The stereoscopic video
processing system 2 detects a motion vector between frames of each
of the right and left input video signals 102, generates
interpolation frames using the motion vector, and generates right
and left output video signals 103. Specifically, the right
frequency converter 20 detects a motion vector between frames of
the right input video signal 102, generates interpolation frames
using the motion vector, and generates the right output video
signal 103. The left frequency converter 20 detects a motion vector
between frames of the left input video signal 102, generates
interpolation frames using the motion vector, and generates the
left output video signal 103. The right and left output video
signals 103 output from the stereoscopic video processing system 2
have a frame frequency of 60 Hz.
[0039] The display 3 receives the right and left output video
signals 103 output from the stereoscopic video processing system 2
and performs frame sequencing by alternately displaying the right
and left output video signals 103 at 120 Hz. The display 3 may be
an LCD display, a PDP display, etc. and is not particularly
limited, as long as it can display stereoscopic video signals. As
described above, the stereoscopic video display system 100 displays
in 3D at 120 Hz after performing frame frequency conversion of the
input stereoscopic video signal 101 of 24 Hz.
[0040] Next, an example will be described where the input video
signal 102 of 24 Hz is converted to the output video signal 103 of
60 Hz by frame frequency conversion (i.e., film dejudder) in each
of the frame frequency converters 20.
[0041] The input image selector 1 outputs the input video signal
102 to the frequency converters 20. At the frequency converters 20,
the input video signal 102 is received at the vector detector 203
and the video memory 202. The video memory 202 is a memory
configured to store at least 3 frames of the input video signal and
output preferred one of the stored frames to the output image
generator 206. The video memory 202 is also configured to output
one frame earlier than the present frame (e.g., the previous frame)
to the vector detector 203. The vector detector 203 divides the
input video signal 102 into blocks of, for example, 8.times.8
pixels, and detects the motion vector of each block by searching
the position having the highest correlation with a previous frame
video signal 104 which is input from the video memory 202.
[0042] FIG. 2 illustrates an exemplary motion vector detected
between two frames of the input signal. As shown, for a target
block selected on frame (1), the position having the highest
correlation with the target block is searched on frame (0) which is
one frame earlier, and the difference between the positions is
detected as the motion vector. In one implementation, the search
may be performed within the range of, for example, .+-.64 pixels
horizontally and .+-.32 lines vertically from the block in which
the motion vector is detected, and the position having the highest
correlation in the range may be obtained. A correlation value may
be the Sum of Absolute Differences (SAD), which is calculated by
summing absolute differences in the entire block between the values
of the pixels contained in the block and the respective values of
the pixels contained in the block to be compared. The size of each
block is not limited thereto, and may be greater or smaller. In
addition, correlation values other than the SAD may be used. As a
searching method, numbers of known techniques for reducing the
processing amount and efficiently detecting motion vectors may be
used.
[0043] Referring again to FIG. 1, the vector detector 203 outputs
to the vector memory 205, a motion vector 110 detected from the
input video signal 102, and the previous frame video signal 104.
The vector memory 205 is a memory configured to store the motion
vector 110 detected by the vector detector 203 and to absorb the
time difference between writing by the vector detector 203 and
reading by the output image generator 206, which will be described
later. The vector memory 205 may have the capacity corresponding to
the time difference. In one implementation, the vector memory 205
stores two motion vectors for two frames of the input video image.
In another implementation, the vector memory 205 stores more than
two motion vectors.
[0044] The output controller 204 determines which one of the motion
vectors corresponding to two frames stored in the vector memory 205
is to be read, which two frames are to be read as the previous and
next frames among a plurality of frames stored in the video memory
202 for generating an interpolation frame, and in which phase
between the previous and next frames the interpolation frame is to
be generated. Based on the result of these determinations, the
output controller 204 outputs control signals. The control signals
include an interpolation phase control signal 107, a frame
selection signal 108, and a vector selection signal 109. Since the
interpolation frames are generated at 60 Hz, which is also the
frame frequency of the output video signal 103, the control signals
from the output controller 204 are also output at a frequency of 60
Hz.
[0045] The video memory 202 receives from the output controller 204
the frame selection signal 108 for determining two frames to be
used for interpolation and outputs to the output image generator
206, the two frames designated by the frame selection signal 108 as
a previous and next frame video signal 105. The vector memory 205
receives from the output controller 204 the vector selection signal
109 for selecting the vector motion to be used for the
interpolation and outputs the selected motion vector designated by
the vector selection signal 109 as a motion vector 106 for
interpolation to the output image generator 206. The specific
operation of the output controller 204 will be described below with
reference to FIG. 3.
[0046] FIG. 3 illustrates an exemplary timing relationship between
the input video signal 102, the previous frame video signal 104,
the detected motion vector 110, the motion vector 106 for
interpolation, the previous and next frame video signal 105, and
the interpolation phases 107. As shown, the output controller 204
outputs the frame selection signal 108, the vector selection signal
109, and an interpolation phase control signal 107 on the following
five frames as one cycle:
[0047] 1) The output controller 204 outputs the frame selection
signal 108 to the video memory 202, instructing the video memory
202 to output frame (0) as the previous frame and no frame as the
next frame in the previous and next frame video signal 105. The
output controller 204 also outputs 0 as the interpolation phase
control signal 107. At this time, since there is no need to
generate an interpolation frame, no motion vector 106 for
interpolation is required.
[0048] 2) The output controller 204 outputs the frame selection
signal 108 to the video memory 202, instructing the video memory
202 to output the frames (0) and (1) as the previous and next frame
video signal 105. The output controller 204 also outputs as the
vector selection signal 109, a signal for selecting the motion
vector detected between the frames (1) and (0) as the motion vector
106 for interpolation. Additionally, the output controller 204
outputs 0.2 as the interpolation phase control signal 107.
[0049] 3) The output controller 204 outputs the frame selection
signal 108 to the video memory 202, instructing the video memory
202 to output the frame (1) as the previous frame and no frame as
the next frame in the previous and next video signal 105. The
output controller 204 also outputs 0 as the interpolation phase
control signal 107. At this time, since there is no need to
generate an interpolation frame, no motion vector 106 for
interpolation is required.
[0050] 4) The output controller 204 outputs the frame selection
signal 108 to the video memory 202, instructing the video memory
202 to output the frame (1) as the previous frame and no frame as
the next frame in the previous and next video signal 105. The
output controller 204 also outputs 0 as the interpolation phase
control signal 107. At this time, since there is no need to
generate an interpolation frame, no motion vector 106 for
interpolation is required.
[0051] 5) The output controller 204 outputs the frame selection
signal 108 to the video memory 202, instructing the video memory
202 to output the frames (1) and (2) as the previous and next frame
video signal 105. The output controller 204 also outputs as the
vector selection signal 109, a signal for selecting the motion
vector detected between the frames (2) and (1) as the motion vector
106 for interpolation. Additionally, the output controller 204
outputs 0.8 as the interpolation phase control signal 107.
[0052] As a result, where the input video signal 102 includes frame
(0), frame (1), frame (2), frame (3), frame (4) and frame (5),
which are used as a reference; the output video signal 103 includes
frame (0), frame (0.2), frame (1), frame (1), frame (1.8), frame
(2), frame (2.2), frame (3), frame (3), frame (3.8), and frame (4).
For example, seven frames of frame (0) to frame (2.2) correspond to
the left and right frames 2 to 8 in FIGS. 5 and 6,
respectively.
[0053] As described above, the output controller 204 appropriately
selects an input frame and a motion vector needed for generating an
interpolation frame and outputs control signals for inputting the
input frame and the motion vector to the output image generator
206. At the same time, the output controller 204 outputs the
interpolation phase control signal 107 to the output image
generator 206.
[0054] The feature amount calculator 207 divides the previous and
next frame video signal 105 used for generating the interpolation
frames into a plurality of image regions of a predetermined pixel
number, and calculates a feature amount 111 in each of the image
regions. The size of each image region may be equal to or different
from the size of each block used for detecting a motion vector.
[0055] When recognizing the binocular disparity between right and
left images, a viewer detects the degree of the binocular disparity
of the right and left images based not on a flat portion, but on a
portion such as an edge which clearly shows correspondence between
the right and left images. Thus, the feature amount 111 may be as a
parameter, for example, a high-frequency component contained in
each of the image regions. The high-frequency component can be
calculated, for example, by the sum of absolute differences between
adjacent pixels in each of the image regions. Alternatively, the
feature amount 111 may be as a parameter, the contrast in each of
the image regions.
[0056] The output image generator 206 generates an interpolation
frame in the interpolation phase designated by the interpolation
phase control signal 107 using two frames input as the previous and
next frame video signal 105, and the motion vector 106 for
interpolation corresponding to the motion between the two frames,
and outputs the output video signal 103.
[0057] FIG. 4 illustrates an exemplary interpolation frame. As
shown, the interpolation frame can be generated by moving pixels or
a pixel block of at least one of the previous and next frames of
the generated interpolation frame along the motion vector 106 for
interpolation. At this time, the position on the time axis in which
the interpolation frame is generated, i.e., the interpolation
phase, can be selected between frame (F-1) and frame (F). For
example, the interpolation frame may be generated using the pixels
moved from only one of the frames such as the frame closer to the
interpolation phase. Alternatively, the interpolation frame may be
generated by mixing the pixels moved from both of the frames at a
predetermined ratio or a ratio corresponding to the interpolation
phase. In the example shown in FIG. 4, the interpolation frame is
generated in an interpolation phase of 1/5 from frame (F-1).
[0058] Furthermore, the output image generator 206 generates an
interpolation image in one(s) of the image regions in which the
feature amount 111 is larger than a threshold, using a block which
is included in at least one of the two frames input as the previous
and next frame video signal 105, and is moved along the motion
vector 106 for interpolation. On the other hand, the output image
generator 206 generates no interpolation image in one(s) of the
image regions in which the feature amount 111 is smaller than the
threshold, but uses the image region of the at least one of the two
frames input as the previous and next frame video signal 105
without change.
[0059] FIG. 5 illustrates the appearance of a stereoscopic video
image created by film dejudder by the stereoscopic video display
system 100 shown in FIG. 1. Specifically, FIG. 5 illustrates the
relationship between time and the display position of a ball, where
the right and left video images of the scene of FIG. 7 are filmed
in 3D at 24 Hz and displayed by the stereoscopic video display
system 100.
[0060] FIG. 6 illustrates the degree of binocular disparity of a
stereoscopic video image created by a film dejudder of the
stereoscopic video display system 100 shown in FIG. 1. The
binocular disparity is caused by deviation of the display position
of the ball from the centers of the lines of sight from right and
left eyes. In FIG. 6, the degree of the binocular disparity between
the right and left images of the input image is N, and the movement
amount of the input image between frames is V. The degree of the
binocular disparity of the output image fluctuates in a range
between N-1/5 V and N+2/5 V among the numerous frames. As compared
to FIG. 10, it is found that with respect to the stereoscopic video
image displayed by the stereoscopic video display system 100 shown
in FIG. 1, the fluctuations of the degree of the binocular
disparity are reduced. As a result, the stereoscopic video display
system 100 can achieve high quality stereoscopic display. This is
because the stereoscopic video display system 100 can generate and
output interpolation frames for the input frames having a great
influence on the binocular disparity and not for the remaining
input frames.
[0061] Specifically, referring again to FIGS. 5 and 11, the
stereoscopic video display system 100 of the instant application
can control the interpolation phases so that two of five frames are
the generated interpolation frames. In contrast, in the
stereoscopic video display system of H09-172618 four of five frames
are the generated interpolation frames in frame frequency
conversion from 24 Hz to 60 Hz. As described above, the ratio of
the interpolation frames, which are contained in the output video
signal and generated using the motion vectors, influences the
degree of deterioration in the image quality if an incorrect motion
vector is detected. Thus, the stereoscopic video display system 100
of the instant application can reduce the deterioration in the
image quality during the frame frequency conversion, as compared to
the stereoscopic video display system of H09-172618. Furthermore,
in the stereoscopic video display system 100 of the instant
application, since the number of the generated interpolation frames
is half, the amount of processing needed for generating the
interpolation frames can be reduced (e.g., halved) as compared to
the amount of processing needed for generating the interpolation
frames in the stereoscopic video display system of H09-172618.
[0062] In particular, as shown in FIG. 6, in the stereoscopic video
display system 100 of the instant application, an interpolation
image is generated using a motion vector in one(s) of the image
regions including a relatively large feature amount, thereby
reducing fluctuations in the degree of the binocular disparity, as
compared to conventional conversion. This enables high quality
stereoscopic display. On the other hand, in one(s) of the image
regions including a relatively small feature amount, no
interpolation image is generated and the original input video
signal is used without change, thereby reducing deterioration in
the image quality caused by an interpolation error.
[0063] Furthermore, the stereoscopic video display system 100 of
the instant application may generate interpolation frames with
phases 0.2 and 0.8. As described above, where the interpolation
phase for generating an interpolation frame is close to the input
frame, the movement amount from the input frame is small, thereby
reducing the influence of an incorrect motion vector. Therefore, in
the stereoscopic video display system 100 of the instant
application, an incorrect motion vector has a relatively small
influence on the image quality as compared to the stereoscopic
video display system of H09-172618 using interpolation phases of
0.4 and 0.6.
[0064] To this end, in the stereoscopic video display system 100 of
the instant application, the ratio of the interpolation frames is
low and the interpolation phases close to the input frame are used.
As a result, the image quality can be less deteriorated even if an
incorrect motion vector is detected. Therefore, the stereoscopic
video display system 100 of the instant application enables high
quality stereoscopic display and reduces deterioration in the image
quality caused by an interpolation error.
[0065] Other implementations are contemplated. For example, while
in the above-described implementations, an example has been
described where the right and left output video signals 103 of a
frame frequency of 60 Hz are generated from the right and left
input video signals 102 of a frame frequency of 24 Hz, the frame
frequencies are not limited thereto. Each of the input video
signals 102 and the output vide signals 103 may have a preferred
frame frequency. For another example, while in the above-described
implementations, an example has been described where the
stereoscopic video signal 101 of 24 Hz is input, the stereoscopic
video signal 101 may be a stereoscopic video signal of 60 Hz
obtained by 3:2 pull-down. If a stereoscopic video signal of 24 Hz
before performing 3:2 pull-down is appropriately selected from a
stereoscopic video signal of 60 Hz obtained by the 3:2 pull-down,
similar processing can be performed.
[0066] The timing relationship among the signals shown in FIG. 3 is
merely an example. Depending on the capacity of the video memory
202 and the vector memory 205, processing can be performed at
different timing. The interpolation phases of the interpolation
frames to be generated are not limited to 0.2 and 0.8. The phases
may be close to these values. For example, the phases may be 0.19
and 0.81.
[0067] Furthermore, the output controller 204 may not immediately
generate the interpolation frames shifted by a 0.2 or 0.8 frame. In
one specific example, the output controller 204 gradually changes
the value of the interpolation phase control signal 107. To this
end, the output controller 204 gradually sets the interpolation
phases of the interpolation frames to 0.2 or 0.8 or close to 0.2 or
0.8 where it is determined that motion occurs between the frames.
Similarly, when generation of an interpolation frame is stopped,
the output controller 206 gradually sets the interpolation phase of
the interpolation frames to 0 or close to 0. As a result, display
with an interpolation frame and display without an interpolation
frame are smoothly switched, thereby improving the image
quality.
[0068] Furthermore, the video memory 202 and the vector memory 205
may not be necessarily provided in the stereoscopic video
processing system 2. Instead, external memories may be used.
Furthermore, while in the above-described implementations, the
stereoscopic video processing system 2 includes the two frame
frequency converters 20, the stereoscopic video processing system 2
may time-share a single frame frequency converter 20 including the
vector detector, the output image generator, and the output
controller to process a right input video signal and a left input
video signal.
[0069] Other implementations are contemplated.
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